The present invention relates to valves, and most particularly to a novel sealing arrangement for a valve wherein the seal ring member is pressure loaded by the line fluid.
Those skilled in the design of valves and valving components are continually seeking to improve and perfect valve constructions. Most particularly, considerable effort has been directed to the design of the sealing arrangements employed therewith. One example of a novel approach to the manner effecting a seal is shown in U.S. Pat. No. 3,563,510; issued to Werner K. Priese, the inventor herein, for a dynamic caulking seal which provides an improved sealing action. The present invention is capable of use to attain substantially the same dynamic caulking action, but is an improvement thereover in that it avoids some of the disadvantages inherent with prior art designs, while providing certain additional advantages not heretofore obtainable.
In the design and construction of a valve sealing arrangement, a number of factors must be taken into consideration. As will be apparent from the discussion to follow, the sealing arrangements employed in valves to date have generally resulted in a compromise as to these considerations. The present invention, is a step forward in that it achieves many of the desired operational features with less of the inherent disadvantages of prior art constructions.
Not too surprisingly, it is known that the best caulking or sealing action wherein a seal ring member is wedged into an annular corner is attained when the seal is constructed of a relatively flexible, elastic material that is easily deformed by line pressure. Seals of this type are adequate where there exists very little relative movement between said seal and the opposed sealing surfaces. However, where a valve construction employs a relatively movable flow control member, against which the seal must engage, these relatively soft elastic materials are undesirable as they wear quickly and soon result in leakage. In addition, with soft material, there is always a danger that should excessively high line pressures be encountered the seal may be extruded past the sealing surfaces. As such, there are a number of considerations which indicate that a certain degree of rigidity must be maintained in the sealing material, with this rigidity increasing as the size of the valve and the line pressures to be handled increase.
Another problem that must be faced in the design of valve components is that of attaining effective, initial sealing contact. That is, an operational sealing engagement must be maintained between the seal and the opposed sealing surfaces at low line pressures, viz., prior to the time wherein the line pressure is sufficiently high to force the seal into caulking engagement. If effective initial sealing contact is not attained, there is a danger that the fluid will leak past the seal initially and as line pressure builds up, the seal will be forced out of engagement with the opposed sealing surface. A rather obvious way of obtaining the desired initial sealing contact is to provide for a substantial amount of primary interference between the seal ring member and the sealing surface as the valve control member is moved to the valve closed position. However keeping in mind the previous discussion regarding the necessary rigidity of the seal ring member, it can be seen that when a rigid material is employed in conjunction with a high degree of initial interference, the amount of force required to operate the valve becomes quite high. This is a distinct disadvantage, especially where the valves are to be operated manually or must be operated rapidly. Here again, the magnitude of the problem increases as the size of the valve and the line pressures to be handled increase.
In comparison to the above-discussed problems, the present invention provides a sealing arrangement that attains a desirable, effective dynamic caulking action under pressure loading at extremely low or high temperatures; provides for an adequate initial seal; provides operational characteristics which permit relatively rigid materials to be employed so as to increase wearability at extremely low or high temperatures; and most importantly attains these advantages without requiring high operating forces. More specifically, the seal construction of the present invention employs an annular seal ring member, which in section, includes first and second leg portions, the former being relatively straight and providing an anchoring flange to be clamped between opposed surfaces of a support groove, and the second said leg portion being of a reverse bent, hook-like arcuate configuration, having a free end. Said reverse bent, hook-like configuration thereby provides an open mouth arrangement which enables line fluid to enter the seal and pressure load said seal into sealing engagement with the opposed sealing surfaces. In addition, due to the employment of the free end portion the seal is relatively flexible and will easily move inwardly of the support groove as it is engaged by the relatively movable opposed sealing surface thereby keeping operating force requirements relatively low. Further, said free end portion is provided with a transversely extending lip means that is engaged with the flange or shoulder on the confronting side wall of the support groove so as to maintain the seal within the groove and preventing unraveling or blow-out thereof, while also controlling the amount or degree that said reverse bent second leg portion extends from said groove. In addition, passage or port means are provided either in the seal or the surrounding valve structure which permit venting of the interior plenum chamber.
During operation, as the sealing surface of the opposed relatively movable member is positioned to confront the seal ring support groove, said surface will engage the protruding bight segment of said second leg portion. Due to a fact that said second leg portion includes a free end, the seal is free to move relatively inward of the groove without creating substantial forces opposing said engagement. When said movement occurs, said transversely extending lip becomes disengaged from the aforementioned shoulder. Due to the inherent resiliency of the seal, there is effected a substantial initial sealing contact. Further, as the lip means becomes disengaged from the shoulder means, there is provided an access path leading from the fluid line to the interior, plenum chamber of said seal ring, such that line fluid will enter said plenum chamber to wedge or caulk the bight segment of said seal ring member into firm sealing contact with the side wall surface of the groove and the confronting annular sealing surface.